Figure 7. Auditory threshold shift caused by noise exposure of rats formerly exposed to toluene (exposure group I). Mean SEM. # indicates that the average auditory threshold after noise exposure (AT4) is significantly (p < 0.05, t-test) higher than before exposure (AT3). * indicates that the average auditory threshold shift is significant (p < 0.05, t-test) when compared to the 0 ppm dosage group.